Television character crawl display method and apparatus

ABSTRACT

A method and apparatus for superimposing printed characters of any such nature as may be transmitted upon a received television image, at the will of the viewer at the receiver. The character information is incrementally transmitted during the vertical blanking interval of the television scanning format. The receiver is especially constructed to have a dynamic shift register, also means to manually select one or none of plural character programs; such as news, stock market, or weather. The characters may be made to crawl horizontally to present an extended message, which crawl may be halted by the viewer. The mandatory display of emergency messages is possible by a control located at the transmitter.

United States Paten 1 Kimura i 1 TELEVISION CHARACTER CRAWL DISPLAYMETHOD AND APPARATUS I75] Inventor:

(73] Assignee: Asahi Broadcasting Corporation,

Osaka. Japan 1221 Filed: June 25,1974

2] Appl.No.:482,922

Hisao Kimura, Kyoto. Japan June 24, 1975 4/1974 Coombe 340/324 AD Miyataet a]. 340/324 AD 57 ABSTRACT A method and apparatus for superimposingprinted characters of any such nature as may be transmitted upon areceived television image, at the will of the viewer at the receiver.The character information is incrementally transmitted during thevertical blanking interval of the television scanning format. Thereceiver is especially constructed to have a dynamic shift register,also means to manually select one or none of plural character programs;such as news, stock market, or weather. The characters may be made tocrawl horizontally to present an extended message, which crawl may behalted by the viewer. The mandatory display of emergency messages ispossible by a control located at the transmitter.

17 Claims, 18 Drawing Figures SHEET PATENTEDJUN 24 ms mmbwmqm COO --OOOCO0 v-v-OOO N OI COO

PATENTED JUN 24 I975 SHEET w OE mum 2:2 hzmzomm TELEVISION CHARACTERCRAWL DISPLAY METHOD AND APPARATUS BACKGROUND OF THE INVENTION Thisinvention relates to multiple images upon a television display tube.

At times the prior art has provided multiple images on a televisiondisplay tube, usually a traveling line of alpha-numeric type at thebottom ofa television image. The purpose has been to present newsflashes without interrupting the television program in progress. Such aline of characters has been transmitted as an integral part of the videosignal forming the image and has been displayed upon all receiverswithout choice or recourse by the viewer.

In such systems the receivers are not modified. Additional requiredapparatus is provided wholly at the transmitter.

In other systems where a choice has been possible by the viewer. theprior art has required a memory at the receiver in which alphanumericcharacters are usually stored, to be called-out for display by a codesignal received from the transmitter. Oriental languages contain about2,500 characters instead of the about 60 alphanumeric characters of thewestern languages. Thus, the code-memory at the receiver system isimpractical for anything other than the storage of under I characters.

Certain other apparatus has been provided by the prior art fordisplaying plural stock market tapes, but without the combination with atelevision image. This is a simple technique, in that exact correlationbetween the timing of the television image scanning and the process forsuperimposing a message is not required.

Still other apparatus has employed delay lines for temporary storage. Acode was used to key-out characters from a receiver memory.

SUMMARY OF THE INVENTION This invention provides a selected one of aplurality of elongated area character messages, or none, superimposedupon the image of a television receiver, at the option of the viewer atthe receiver. This is accomplished by providing additional apparatus andmanual controls at the television receiver. A mandatory display ofemergency messages is also possible and this is under the exclusivecontrol of the transmitter.

At the transmitter, digital logic, including a clock generator, pluralregisters and memories for each character pattern, memories for message,counters, and decoders from the character signals. These areincrementally transmitted during successive vertical blanking intervalsof the known television image signal (video). The character signalitself directly provides the information required for the display at thereceiver.

At the receiver, in addition to the known television circuits, there isprovided digital logic, including a character signal data extractor,buffer registers, character element counters, and a large dynamic shiftregister. These are interconnected by suitable gates and flipflops. Avideo data mixer reinserts the characters signal into the video channel,this signal having been read-out of the shift register at a time to bedisplayed at a selectable vertical position on the television imagedisplay device to be seen by the viewer.

Manual controls at the receiver allow one of a plurality of charactermessages, or none, to be selected for viewing, also to stop thehorizontal crawl of the message, if desired.

The characters displayed are formed by low "high" electrical bit pulsessupplied to the television image reproducing device. These are suitablytimed to form the characters in synchronism with television scanning.These may be alpha-numeric in any language, Japanese or Chinesecharacters, or any suitable diagrams or representations.

A flag identifies the initiation of character data transmission andpromotes simplified apparatus at the receiver.

Typically, all character data are transmitted, incrementally andsuccessively, upon one line of horizontal television scanning during thevertical blanking interval.

A dynamic shift register temporarily stores thousands of bits that havebeen incrementally transmitted from the transmitter. These form inthemselves the character display at the receiver.

Accordingly, permanent memory storage apparatus is not required at thereceiver and the information required for the display is not drawntherefrom by merely a transmitted code. The method of operation of thesystem is thus widely removed from the conventional mode of operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I shows the face of a displaytube with a representative display thereon and indications of otherpositions which the display of the line of characters may occupy.

FIG. 2 shows how the letter E is formed on the television raster byappropriately timed bit signals.

FIG. 3 shows the entire transmitter system block diagram.

FIG. 4 shows a segment diagram of a 9l bit shift register, as asimplified example.

FIG. 5A shows related shift pulse trains to the shift register.

FIG. 5B shows display element addresses on the television raster.

FIG. 6 shows the contents of the shift register shifted by I bit.

FIG. 7 shows the horizontal crawl sequence of sample letters A B C.

FIG. 8 is a waveform and channel allocation diagram for the 21sthorizontal line.

FIG. 9 is a schematic diagram of the transmitter character-signalforming logic.

FIG. 10 shows a detailed schematic diagram of u, w and W counters.

FIG. 11 is a block diagram of the receiver charactersignal forminglogic.

FIG. 12 shows a functional block diagram of a portion of the receiversystem.

FIG. 13 shows a raster representation of the receiver functioning.

FIG. 14 is a representation of receiver system timing.

FIG. 15 is a further portion of the functional block diagram of thereceiver system.

FIG. 16 is a schematic logic diagram of the receiver character-signalforming logic.

FIG. I7 is a schematic logic diagram of the apparatus for accomplishingmandatory control".

GENERAL FIG. 1 shows the television display for this system, includingthe timing relationship for the known television scanning from left toright and top to bottom, respectively, Numeral 1 shows a field startedwith a vertical drive signal and completed just before the verticaldrive signal of the next field. Numeral 2 shows the frame of the rasterand 3 indicates a significant part of the normal televised picture.Numeral 4 indicates a typical sub-raster, dimensioned as 16 lines perfield, or a total of 32 lines for the full frame of the display systemof this invention. Numeral 5 shows a typical superimposed font of thisdisplay system; i.e., the message "Electronic Display is popular.

Other positions, such as 7 and 7', are selectable for positions of thesub-raster.

The display normally crawls in the direction indicated by arrow 6. Theletter E of the message starts to crawl from the right end of sub-raster4 and travels to the left, where it is now shown.

The television image may be reproduced in color by the known televisionprocess. No interference between the display waveforms and the waveformsrequired for color television is experienced.

Numeral 8 shows the transmitted data signal, superimposed on the 2 Isthorizontal line, just above the top of the raster frame 2. The exactnature and composition of this signal varies with the details of themessage.

In FIG. 2, the capital E of the above illustrated message is identifiedby numeral 9. It is divided into a number of vertical columns, such asten, as shown. Pattern data bits (PD bits) in the first (left) column 10are l, I, l, l, l, to a total of l2, from the top down to the bottom ofthis letter. Thereafter, 0, 0, 0, 0. This is sent in the firsttelevision scanning field.

In the same manner, the second column, ll, becomes 1,0, 0, 0, 0, l, 1,0,0, 0, 0, l, 0,0,0, 0, and this is sent on the second field. Continuing,the third column, 12, is sent on the third field, and so on; to thetenth column identified by numeral 13. These columns of PD bits are animportant aspect of the system of this invention.

it will be noted that there are four 0 spaces at the bottom of eachcolumn on the E. This sets the bottom of that letter and others like itsufficiently far up in the sub-raster so that lower stems of certainsmall letters such as the p and y can be executed.

TRANSMITTER MODE The block diagram of FIG. 3 gives the method andapparatus involved in adding the character display to known televisiontransmitting apparatus.

Character coder I4 is the input originating device for coding a largenumber of characters, such as 2,500 Chinese characters. By pointing witha known light pen each character can be coded as a 6 bit X two frame, ora 12 bits code. The operator selects the character according to thesentence he is forming for transmission.

Sentence memory 15 is connected to character coder 14, for the storageof the coded data output from coder [4. These data are stored in addresssequence. For the sending sequence the stored data in sentence memory 15is read out in address sequence according to the time lapse for eachletter covering the entire sentence.

At the end of the sentence memory 15 is programmed to address back tothe beginning of the sentence.

The output of sentence memory I5 enters character pattern memory 16. Thelatter is a magnetic core memory. having a capacity of 131 K bytes. Atotal of 2,500 character patterns are stored therein, in a l6 X 16 arrayfor each character. The core memory is segmented as 1,024 lines for theX axis. 64 lines for the Y axis, and 16 bits for the Z axis.

X address register 17 is connected to character pattern memory 16 as isx address counter 18. These select the 1,024 lines having to do with theX axis.

Y address register 19 is also connected to character pattern memory 16.This register selects 64 lines having to do with the Y axis, subsequentto the selection for the X axis.

Six bits two frames of a character are assigned for the X and Y addressregisters, and its l6 columns for the x address counter 18.

Sixteen bits for the Z axis correspond to the vertical PD bit of eachcolumn.

In the address of the core memory that corresponds to the code of eachcharacter, the pattern for the character is previously stored.

Buffer register 20 is connected to the output of character patternmemory 16. The display is normally a horizontally crawling format andthe coded characters from the sentence memory are converted intovertical column PD bits, 16 bits, and sent out for every field, V.Accordingly, x address counter 18 is set to zero at the beginning of thecharacter and the PD bits in the left end of the character are read fromthe Z axis and temporarily stored in the 16 bits capacity bufferregister 20. This register holds the data until a selected line,typically in the vertical blanking period of the television raster, suchas the 21st television scanning line, 21H, occurs, and then the data aresent out serially on that line. At the same time x counter 18 is steppedup one, and the second vertical column PD bit is read out to be ready tobe sent out on the followingV 2lst line. In the same manner, onecharacter is completed with 16 vertical PD bits upon 16 V periods havingoccurred.

The following two V intervals do not have an output from charactermemory 16, but sentence memory 15 is addressed out one step and the nextletter code set in the X and Y registers. This two V interval becomesthe space between characters. The above operation is then repeated inorder to send out the entire sentence.

Encoder 21 is connected to the output of buffer register 20, and theencoder accomplishes the above process. The output of the encoder isconnected to mixer 22.

Mixer 22 also receives an input from program-line 23, upon whichtypically a full color video signal flows. The output of the mixer istaken by the on-air-line 24 and thence to a television videotransmitter, pay television cable, or other apparatus that conveys thefull transmitter signal to receivers for viewing.

RECEIVER MODE The previously mentioned column PD bits are extracted inthe receiver, stored for accumulating a certain amount of data,processed for display and then displayed.

In order to simply explain the mode of receiver operation, a displayarea of l3 X 7 bits is chosen. A stored capacity of 91 bits is thusrequired. This is accomplished by shift register 30, shown in FIG. 4.

The input 3l of shift register 30 is switched to either new pattern data33, or the output 34 of the shift register through recirculation line 35by means of appropriate actuation of transfer switch 32.

The various segments 36 of shift register 30 begins at number 0, numberI, etc. from the upper-left output side of the register. They progressto number 90 at the lower-right input side of the register.

The output of the shift register 34 is fed to display means 37, which isshown as the known television cathoderay tube. When the output of theregister is high; i.e.. a digital I, then a white (bright) dot appearson the television screen and an elemental part of the character displayis formed. When the output of the register is low; i.e., a digital 0,there is no contribution to the image television signal.

In FIG. 4 the data bits are given a designation corresponding to theirposition in the shift register. These start at the upper-left, output,end of the register with Al, then Bl, Cl etc. to M1 in the top row inthe illustrative example of this figure. Similarly, the second rowstarts with A2 and ends with M2; and so on, until the end of the lastrow is M7. Each of these designations may be a l or a 0, according tothe data required to reproduce the characters of the message.

Going further, in FIG. 5A pulse train 38 is generated for the durationof one horizontal line, say the Kth line; kth H. It is fed into theclock pulse input of shift register 30 as the shift pulse.

In the recirculation mode, Al is seen at the beginning of the kth Hline. Shift pulse SI is then added and B1 is shifted into the No.segment of shift register 30. At the same time BI is seen on displaytube 37. Also, previous data bit Al is fed back into the No. 90 segmentvia recirculation line 35 and data transfer switch 32. With the nextshift pulse S2, Cl is seen on display tube 37.

In this manner, as shown in FIG. 58, Al through Ml are displayed on thekth H line, identified by numeral 39 in that figure, by the train ofshift pulses SI through SI3. This occurs in synchronism with televisionscanning.

Then A2 is shifted with Sl3 and MI is stored in segment No. 90, at thelower right in FIG. 4.

On the (k I) the H line, identified by numeral 40 in FIG. B, the sameshift pulse train 38 of FIG. 5A is applied to shift register 30, and thesame result occurs as has been explained for the k the H line.Similarly, this result occurs again for each of the lines shown in FIG.58, as the (k 2) th H line to the (k 6) th H line, in this simplifiedexample.

The contents of the shift register are displayed on the picture tubescreen 41 of FIG. 58. They appear as the desired characters inaccordance with the initial data.

Shift register 30 in the recirculation mode can hold back the data tothe same location as long as the number of shift pulses equals the shiftregister length.

In other words, data are displayed once in the scanning duration of thek th H through (k 6) th H lines on screen 41 of the display device. Aslong as the data a recirculated back to the original segment location inthe shift register 30 itself, the display is seen as a still display,having the formation of data Al through M7 in FIG. 4.

Normally, when the chain of display of data Al through M7 has beencompleted (hereinafter designated as the end of an event") oneadditional shift pulse designated q is applied to shift register 30.

The content of data in the shift register shown in FIG. 4 becomes thatshown in FIG. 6. It is seen that each datum has been shifted one segmentlocation to the left, except the data segmented on No. [2. No. 25, No.38. No. 90. With one more pulse operation of the above these data willbe displayed.

In the process heretofore outlined the previously displayed datum Al isrecirculated into No. 9() segment through data transfer switch 32, butnow, at that particular moment switch 32 is turned to accept a new datumA7 (not AI). In the same manner. new datum Al is an input by the time 13shift pulses have occurred. In this way the last datum is replaced andwritten by new datum A6. As a result, the whole display is shifted 1column bit to the left and the extreme right column of the display isrefreshed with new data. By the continuation of this operation thecharacter message is made to crawl from right to left.

Recapitulating, the sequence to accomplish the crawl operation is asfollows:

I. display of the event,

2. insertion of the q pulse for each television field.

3. write new data for each field.

The order of the sequence does not affect the operation as a whole.

If the input to display tube 37 is gated off from the output 34 of theshift register the display disappears. However, the process of writingin new data can be accomplished independently of any display of it.

Crawl of the characters can be inhibited at the television transmitterby sending out the control signal of the q pulse insertion, because theq pulse is generated in the receiver. The speed of the crawl can also bedecreased by controlling for less frequent insertion of the q pulse thannormal. The display may also be frozen; i.e., the crawl stopped, by notinserting the q pulse to the shift register at the receiver.

A representation of how the crawl operation appears is given in FIG. 7.It shows a portion of the message characters ABC in the Englishalphabet. The top row 42 shows the data bits Al, Bl, Cl, to M7 for allof the A and B and the first stroke ofC. In the second row, 43, databits Al, A2, A3 A7 have been added and the display has moved one dataposition to the left of what is shown in the first row. The same processis repeated for the successively lower rows, 44, 45 and 46, and it isseen that the A has been reduced to a line and the C is now complete.

CHARACTERISTICS OF AN ACTUAL EMBODIMENT The illustrative simpleembodiment heretofore employed to set forth the method and the majoraspects of the apparatus is modified in ways as follows in order tobecome a full-scale device.

For characters of the Chinese type an area of 16 X 16 bits is typicallyemployed. For English and other alphabet letters an area of 10 X 16 bitswith a 2 bit spacing is considered proper for the display, in view ofthe size of the characters and the number of characters in one line.

Typical crawl speeds then become as follows. For Chinese characters thewidth of the area plus a spacing of 2 bits is a total of I8 bits. Withtelevision fields per second and a l bit shift per field, as indicatedin FIG. 7 the crawl speed for Chinese characters becomes 60/18 333characters per second, and for alphabet characters becomes 60/12characters per second.

A desirable vertical extent of pattern data bits includes 32 horizontalscanning lines over one frame; l6 in each field. Considering the aspectratio of the character and the speed of television scanning, the clockfrequency of the shift pulses may be altered to be twice that of thecolor sub-carrier, 3.58 megahertz (MHz), thus to be THE; MHz.

The formation of the sub-raster may typically require 16 X 250 bits=4096 bits storage capacity in the receiver. This provides thecapability of displaying 14 Chinese characters or several words inEnglish on one line.

There are numerous different vertical positions on the televisionviewing screen for the sub-raster which carries the character message. Anet viewing raster typically contains 525 lines minus 2 X 2l lines forthe vertical blanking. The sub-raster is 32 lines high in each frame.There are thus (525 21 X 2)/32 15 bands available.

However, since it is common television practice to mask off all aroundthe edge of the raster from the view of the observer. and since allpossible positions for the sub-raster are not aesthetically desirable,about six positions are considered proper.

As will become further evident later, more than one message can betransmitted and utilized at the will of the viewer at the receiver. Allmessages are available at the receiver, and any one, or none, isselected by the viewer by manual control.

A typical number of separate messages is five; such as weather reports,stock market quotations, news, etc. These are all transceived over the21st horizontal. H, line. A suitable clock frequency for thistransceiving is half the color television sub-carrier frequency, or 1.76megahertz. This allows a sufficient margin for the television videoband-width.

In the widely used manner of regenerating synchronizing signals in atelevision receiver, often known as a.f.c. horizontal synchronization,these synchronizing signals are not precisely in phase with thesynchronizing signals that are transmitted. Thus. the television picturereproduced at the receiver may shift slightly with respect to thecathode ray tube reproducer. It is not; however, distorted.

For transceiving character data, critical accuracy of phasing in thisaspect is required. According to this invention an additional pulseknown as the initial flag" (pulse) is generated. It is timed to be, andis, inserted ahead of the series of character data transmission signals.It achieves the critial accuracy required at the receiver, so that thecharacters of the messages will be clearly formed. The complexity, andso the cost, of the receiver character handling apparatus isconsiderably simplified through the use of this pulse.

TIMING RELATIONSHIPS OF TRANSCEIVING The timing relationships foraccomplishing transmis sion of character data and the scheme involvedare shown in FIGS. 8, 9, 10.

In FIG. 8, numeral 50in a row, indicates the channel assignment of thevarious messages, such as weather, news, etc. This is on the 21sthorizontal line. This is a preferred line, being at the end of thevertical blanking period and thus devoid of the video signal forming thetelevision image. In general, another horizontal line. or even lines, inthe vicinity may be used. with understandable adjustment or minormodification of the apparatus involved in handling this part of theprocess.

As will be seen, line is divided into seven channels; 0W, 1W, 6W. Allhave 18 divisions at the period of 0.5587 microseconds, corresponding tothe frequency of 1.79 megahertz, except channel 6W. The latter is ofresidual nature.

Channel OW starts at the leading edge of the horizontal (H) syncronizingsignal and holds until slightly over the termination of the horizontalblanking signal. Therefore, no character data signal can be assigned tochannel OW. However, the last portion of it, identified by numeral 51,is used as the initial flag pulse for the synchronization of thecharacter data signal in the receiver.

Channels IW through 5W are used for the allocation of the A, B, C, D andE roll character message data.

Channel 6W contains only 5.75 divisions instead of 18. It terminates atthe leading edge of the next H syn chronizing pulse, and this channel isnot used for data transmission.

The diagram identified by numeral 52 shows the control bit region lWo,2W0, etc., which is formed of 2 bits, and the character data bit region1W 2W etc., which is formed of l6 bits.

The diagram identified by numeral 53 gives the detail of one channel.Therein, S4 is a spare (unused) bit, 55 is a freeze bit, and theinclusive 56 numeral indicates the pattern data bits.

If the freeze bit 55 is in the I state, the insertion of the q pulse onthat field is inhibited in the receiver and the character display isfrozen (not allowed to crawl) for that scanning field for that channel.When that is the case, data are not to be transmitted in that channel.Both the space bit and the freeze bit may be programmed to controladditional modes of operation, besides the basic mode mentioned.

The waveform identified by numeral 57 in FIG. 8 gives details for theline 21st H. Initial flag pulse 58 is the detail of the indication 51 onthe numeral 50 row. The variations inclusively indicated at 59 comprisethe data of the No. l channel. These waveform variations areaccomplished in buffer register 20 and encoder 21 of FIG. 3.

TRANSMITTER APPARATUS FIG. 9 shows the transmitter character-forminglogic, notably buffer register 20 and encoder 21.

For simplification of explanation FIG. 9 has been drawn for positivelogic, regardless of the conventional integrated circuit (IC) system oflogic. That is, flipflops and counters are enabled or cleared by thepositive-going edge of the clock pulse or clear pulse. The outputs ofgates are not inverted.

For reducing the influence of the frequency interleaving of the NTSCstandards, the color sub-carrier frequency fs is frequency-doubled to2fs=7.l6 megahertz.

This frequency, at 60 in FIG. 9, is fed into u-counter 61, where it iddivided 4 times, to fs2,=l .79 MHz. This frequency, which is the clockfrequency for the data transmission, is fed into following w-counter 62and subsequently W-counter 63. These counters generate various timingpulses, shown at the top of each. as to the outputs.

1. The method of displaying characters upon a television screen inaddition to displaying a television image, which includes the steps of;a. incrementally formulating character-forming information (8) duringthe interval of time not required for forming television imageinformation, b. temporarily storing said character-forming information,c. gating-out said stored character-forming information at a time otherthan during said interval of time, d. combining the gated-outcharacter-forming information with said television image information,and e. displaying said characters and said television image forsimultaneous viewing.
 2. The method of claim 1 which additionallyincludes; a. recirculating (35) the temporarily stored character-forminginformation.
 3. The method of claim 1 in which; a. said interval of timenot required for forming television image information is the verticalblanking interval of the television image-scanning raster.
 4. The methodof claim 1 in which; a. said interval of time not required for formingtelevision image information is that occupied by only one horizontalline (57) of the television image-scanning field.
 5. The method of claim1, which additionally includes; a. incrementally formulating pluralgroups (52) of character-forming information at different times duringone said interval of time not required for forming television imageinformation, b. selectively gating-out only one said group (1W), and c.displaying only characters reproduced from said group with saidtelevision image.
 6. The method of claim 2, which additionally includes;a. adding new information and discarding old information at each saidrecirculating of the stored character-forming information to cause thereproduced character to move with respect to the reproduced televisionimage, and b. adding control information for selectively inhibiting themoving of said reproduced characters.
 7. The method of claim 6 in whichsaid temporarily storing step includes; a. successively temporarilystoring (1 Wo) an increment of said control information, and b.subsequently temporarily storing (1 W1) plural increments of saidcharacter-forming information.
 8. The method of claim 1, whichadditionally includes; a. selectively forming a mandatory control pulseduring said interval of time not required for forming televisioninformation, and mandatorily gating-out character-forming informationfollowing the occurrence of said mandatory control pulse.
 9. The methodof claim 8 in which; a. said mandatory control pulse effects gating-outsaid character-forming information following the occurrence of saidmandatory control pulse independent of a setting of the manual controlof the character-displaying apparatus to the off, freeze, condition. 10.Apparatus for displaying characters upon image display means in additionto displaying a television image thereon, comprising; a. first means(23) to form television image information, b. second means (14-21) toformulate character-forming information, and control information, c.third means (22) to incrementally combine said character-forminginformation and said control information with said television imageinformation, during an interval not required for forming said televisionimage information, d. fourth means (150) to subsequently separate saidcharacter-forming information and said control information from saidtelevision image information, e. fifth means (160) coactive with saidfourth means to accept said character-forming information during aninterval of time not required for displaying television imageinformation, and to temporarily store said character-forminginformation, f. sixth means (180) connected to and coative with saidfifth means to read-out said character-forming information during thedisplay of television image information, and g. display means (190, 125)coactive with said first means and said sixth means to reproduce bothsaid characters and said television image for simultaneous viewing. 11.The apparatus of claim 10, in which said second means includes; a. abuffer-register (20) to accept character-forming information insuccessive bits, b. a clock (60, 61) to actuate said buffer-register,and c. a counter (63) to time the acceptance of said bits by saidbuffer-register (20).
 12. The apparatus of claim 10, in which said thirdmeans includes; a. a decoder (86) to render said character-forminginformation available, and b. three-terminal isolative mixer means (22)to combine said television image information and said character-forminginformation.
 13. The apparatus of claim 10, in which said fourth meansincludes; a. a first flip-flop (154), b. differentiating means (155)connected thereto, and c. a second flip-flop (156) connected to saiddifferentiating means to block out said television image informationfrom the output of said fourth means.
 14. The apparatus of claim 10, inwhich said fifth means includes; a. a small plurality bit bufferregister (160) to accept said character-forming information during saidinterval not required for forming said television image information. b.a larger plurality bit shift register (180), and c. clock means (170) toactuate said shift register during the display of said television imageinformation.
 15. The apparatus of claim 10, in which said sixth meansincludes; a. gate means (191) connected to said fifth means and to saiddisplay means (125), and b. flip-flop means (171) connected to said gatemeans and to counter means (172), to cause saiD read-out to occur duringthe display of said television image information.
 16. The apparatus ofclaim 10, in which; a. said second means includes a plurality of meansfor data bits (66-70) and for control bits (90-94) to sequentially forma corresponding plurality of separate character-messages, and b. saidfourth means additionally includes channel selective means (150) for theselective display of one of said channels upon said display means (125).17. The apparatus of claim 10, in which; a. said second means includescontrol-pulse-forming means (90-94, re 54, 55) of selective output, andb. said sixth means includes readout means (402, 406) responsive to aselected control pulse configuration, whereby read-out of saidcharacter-forming information is mandatory.